This invention relates to morphometric analysis of anatomical tomographic data, e.g., in vivo volumetric measurement of regions of the human brain.
Precise quantitative volumeric measurements of central nervous system morphology are necessary to obtain objective assessments of major nuclear structures and gray-white matter abnormalities involved in various disease processes. Numerous in vitro quantitative techniques are currently available for evaluation of brain morphology, but these are limited to use in postmortem tissue, often leading to error from the unpredictable variability in tissue fixation procedures. A specific method of in vivo quantitative analysis of brain morphology has not previously been available. Morphometric reconstruction from computerized tomographic data has been limited because of relatively low resolution, and X-ray scatter at bony interfaces.
Prior efforts at morphometric analysis of tomographic data have tended to rely on manual procedures. For example, feature outlines have been drawn by hand; areas have been determined by projecting a tomographic image onto a wall on which graphical divisions appear and manually counting squares within the region of interest; outlines have been drawn manually by cursor movement on computer displays, with attendant inaccuracy and tedium; volumetric measurements have been roughly estimated based on two-dimensional measurements and assumptions about the shape of the feature (e.g., that it remains an ellipsoid).
Tomographic images of the body tend to be difficult candidates for image processing because the boundaries between regions are not sharply defined, and because there are sometimes large variations in intensity within regions. The difficulty is especially pronounced in the case of selecting a boundary between adjoining regions of soft tissue (e.g., between the cortex and white matter of the brain).
Improved morphometric analysis techniques may be useful in recognizing regions of abnormality in patients suffering from disorders, e.g., developmental language disorders (DLD or dysphasia) and autistic spectrum disorders (ASD), for which no abnormalities are typically observable from mere visual interpretation of MRI scans.